The planes were spotted before they entered the air defence identification zone, defined as a broader area in which countries police aircraft for security reasons but which does not constitute their airspace.
China’s defence ministry later said it had organised drills with Russia’s military according to “annual co-operation plans”.
The drills took place above the East China Sea and western Pacific Ocean, the ministry said, calling the exercises its “10th joint strategic air patrol”.
Moscow also confirmed the exercise, saying that it lasted eight hours and that some foreign fighter jets followed the Russian and Chinese aircraft.
“At certain stages of the route, the strategic bombers were followed by fighter jets from foreign states,” the Russian Defence Ministry said.
Since 2019, China and Russia have regularly flown military aircraft into South Korea’s air defence zone without prior notice, citing joint exercises.
In November last year, Seoul scrambled jets as five Chinese and six Russian military planes flew through its air defence zone.
Similar incidents occurred in June and December 2023, and in May and November 2022.
China and Russia have expanded military and defence ties since Moscow ordered troops into Ukraine nearly four years ago.
Both are also traditional allies of North Korea, Seoul’s arch-foe.
– Agence France-Presse
